Reversing the polarity of dynamo-electric machines.



PATENTED MAY 28, 1907 4 J. B. TAYLOR. REVERSING THE POLARITY OF DYNAMO ELECTRIC MAGHINES.

APPLICATION FILED SEPT.Z9.1904.

/ (D e f INVENTOR John BT51 lor,

fltty I n Y. s,

' S- %5T Eric.

JOHN Bl TAYLOR, or soHENEcrAnY, NEW'YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION ,orNnw YORK.

"FiEVE'RSING THE PoLAsirY OF ovnmaoozrscrsio MACHINES.

Specification of Letters Patent.

Patented. May 28, 1907.

]'0 a, whom it may concern.-

Be it known that I, J OHN B. TAYLOR, a citizen of the United States, residing at Schenectady, county of Schenectady, State oi,New York, have invented certain new and useful Improvements in Reversing the Polarity of Dynamo-Electric Machines, of which the lollowing is a specification.

My prcsen t invention comprises a method of changing the'polarity of self-exciting synchronous machines such as rotary converters. To accomplish-this result I provide means for reversing the field connections of tliO Inachine, and by suitable manipulal ion produce the change of polarity desired.

i y inveinion will be better understood by reference to the following description taken I in connection with the accompanying draw- I to the field insulation, is prevented.

" 21, and the other 22,

ings representing diagrannmnically one cmhodnnent of my invention.

The scope of the invention will be pointed particularity H1 the appended out Wi'th claims. I

In the drawings, the armature of a rotary converter is indicated conventionally at 1. The alternatingcurrentniains associai cd. with the armature are shown atZ, 3 and 4, and'ihe corresponding direct currontmains at 5 and 1 6; The field coils of the rotary c nvertcr are shown at 7, 8-, 9,10, ll and 12, but [he field magnet frame, for convenience oi lllllSll'ittion, lSOIlIlL'LGd. These coils are connected to a reversing switch 13 by which the current through the coils may not only be ecwrscd but its circuitr between adjacent coils llltfi' 'rupted. By thus breaking up the field circuit theproduction therein of high voltages 'by,the transformer action of the current in the armature during starting or at other times, and a resultant danger oi break down The rcversing switch is such as to perform the double operation of breaking up the field when the switch is in the open circuit position and of reversely connecting the held when thrown from one closed position to the other.

The movable switch arms of the reversing switchare indicated at i4, 15, i6. and i7, and E these cooperate with two sets or nxed con tacts, one set being numbered 18, 19, 20 and L3, 24 and .35. it will be seen that when theswitch is thrown so as to engage the contacts 22 to 25, the field coils -are connected in series witheach other across r machine.

the direct current leads 5 and 6 and with the 5'5 shunt held resistance box 26 included. \Vhen thrown to the other position the coils are connected directly across the leads and 6, with the resistance box omitted, and in such a manner as to be traversed by current of the opposite direction. In the intermediate position of the switch the circuit of the held coils is not only opened but is broken up so This operation oi starting is performed with the field circuit open. it the armature locks into synchronism so as togive the desired polarity across the direct current end of the machine, then the held switch is closed in normal position so as to connect the hold winding across the direct current end of the. it, l10\\'0- \'(1, the machine locks into synchronisni with a reversed polarit at the direct current end then, in order to re verse the polarity, I throw the field switch 13 in the opposite direction so as to connect the iicld coils in reverse relation to the supply current from the connnutator oft-he machine. 0 As the'polarity ol" the lield is. thus changed the armature of the machine slips back in phase and tends to assume aposition ap' proximately onc' quartcr of a period behind I that corrcspondi'ng to normal running. As the armature drops back, the commutation which heretoiiirc took place at the peaks of.

the alternating. current waves, slides down these waves so to speak, uiitil the zero point is reached. The excitation of the machine at this point becomes zero. The friction, wind; age, etc. acting on the armature tend to cause the armature to drop back in phase still far-- ther, whereupon the direct current voltagetends to increase from zero in the opposite direction. The reverse polarity of the field. thus produced opposes anyfurther shift in phase, and the machine tends thus to remain- IOO ma be as stron J throw of the switch to normal position puts in a condition, in which the connnuta-tion' takes place at a point ust sul'liciently reimoved from the zero point of the alternating current waves to hold the armature in equilibrium. it now, the held switch be reversed, the armature will then he attracted bacluvard and wil look into position one pole hack of that corresponding to the initial condition. sponds to an opposite polarity of the direct current side oi the machine, and the desired result is thus accomplished.

In Order to .acilitate the operation of reversing' the polarity of the machine, i or eh comiectioi so that the re uit when the ii;

variable under this CODCU' g as oosshle.

the hex in circuit ready for use.

shift the phase of a svnchronous machine E halt a o reversii ween done we and is a p r Lem n that herein describe or the rea citation. is not altered. as the h owe r, cited in hat I byLctters latent ot the Lmiteu St 1, lire method of reversingthe pclari a self exciting alternating current inaclun0, 3 the I ire the f The return aware that it has beerrproposeci to i This, i

phase more than one-quarter o" of the ightly in the opposite direction, and. their reversing;

the direction of current flow in the field Wino ings.

3. The method of reversing the polarity of g a self exciting alternating current machine l-dri'ven 'by alternating currents, which con- 1 slsts in connecting; the field revcrsely and then in normal relation to the source of excitation.

4. The method of reversing the polarity of i a rotary converter which consists in first pro- 5 5 during a reversed polarity of the field, allowing the direct current voltage to fall to zero 1 and then to rise slightly in the opposite dif rection, and then reversing the field excita- 1 H011, l or rho method of reversing the polarity of converter which consists in remg the field circuit a multi- .oints, aril then charwh the con i H converter provided with a iield y-osral, which consists in roversely conting the lipid and at the same time omitrhrwstat from circuit, and. then v N r s 1 the circiu": "(0 their 12 urinal conchthe rlwrw t in circuit.

iaiion o1? dynamo electric oi lield poies, and

1 means Mr opening the ci cuit oi the field. at 75 one or inurc points between the iield poles and than i'riV irililf, closing the circuit.

if combination ol dynamo electric "1:: provided with plurality of field till in the field circuit, means ircuit, and for re as to leave the rheo no connecti 1 out of circuit.

.ri t ness wherer nand this 26th. do:

- .lbl'li'l we heroin to set in 85 i 

